In an evolved packet system (EPS), a serving gateway (S-GW) and a packet data network gateway (P-GW), as forwarding plane network elements, have both a forwarding function and a logic control function. Because load of the forwarding plane network elements is relatively heavy, the OpenFlow protocol emerges. The OpenFlow protocol changes conventional physical fixed hardware into a dynamically programmable software defined network (SDN), and separates a control plane network element of a gateway from a forwarding plane network element. The control plane network element controls the forwarding plane network element by using the OpenFlow protocol, so that the forwarding plane network element forwards a service flow. Each service flow includes a plurality of different packets.
In the prior art, an SDN concept is introduced into an EPS core network, namely, an evolved packet core network (EPC), and a network structure in which a control plane network element GW-C of a gateway is separated from a forwarding plane network element GW-U is obtained. As shown in FIG. 1, a control plane network element GW-C01 and other control plane network elements such as a mobility management entity (MME) 02, a policy and charging rules function (PCRF) device 03, and a home subscriber server (HSS) 04 are deployed in a centralized manner. The control plane network element GW-C01 is configured to decide a processing rule for packets of a service flow of user equipment (UE), and send the processing rule to a forwarding plane network element GW-U05 by using an interface (the interface may use the OpenFlow protocol) between the control plane network element GW-C01 and the forwarding plane network element GW-U05. Then the forwarding plane network element GW-U05 processes the packets of the service flow of the UE according to the processing rule, and sends the processed packets of the service flow to an external data network 06. In FIG. 1, a base station 07 first sends the packets of the service flow of the UE to a backhaul network, namely, a backhaul network 08, and then the backhaul network 08 sends the packets to the forwarding plane network element GW-U05. Because the backhaul network 08 forwards the packets of the service flow based on an IP address, an IP address of the forwarding plane network element is bound with the corresponding forwarding plane network element, so that the packets of the service flow of the UE are smoothly routed to the corresponding forwarding plane network element.
In a process of implementing the present invention, the inventors find that the prior art has at least the following problem:
In an actual deployment scenario, for example, in a data center cloud platform or a network function virtualization (NFV) platform, a forwarding function is deployed in a form of a virtualized network function (VNF). Because the VNF is characterized by a dynamically scalable capacity, a service flow may need to be frequently redirected between different VNFs. However, because an IP address of a forwarding plane network element is bound with the corresponding forwarding plane network element, and the IP address needs to be bound and unbound in a service flow redirection process, the service flow cannot be frequently redirected between different VNFs smoothly. Therefore, flexibility of service flow forwarding is relatively low.